Well, I think that you have the right to use the names of your own heritage, whether you live and breathe the culture or not. Otherwise, they will die off.
And, like another said, the name
Kieran doesn't exactly scream "IRISH!" - it's a gentle Irish name, and that's very fashionable. It's ok to use names for pure aesthetic reasons. How many little girl Mackenzies out there do you think have a familial reason for being given that surname? Not very many, I'd wager.